The objective of the proposed research will continue to be to expand knowledge and understanding of the interaction of ecological and environmental factors that allow arboviruses to be maintained in their basic transmission cycles and to be transmitted tangentially to human populations. Research will provide a basis for develoment of alternative or improved approaches to control arboviral diseases and for arboviral surveillance. Special attention will be given to the influence that the """"""""greenhouse effect"""""""" may have on arbovirus transmission cycles. To achieve this goal, six short-term and interrelated Specific Aims are proposed for intensive study in the next five years: 1) To assess the possible future impact of the """"""""greenhouse effect"""""""" on arboviral ecology in southern California and the central valley of California by studies on the effect of temperature on selected biological traits of Culex tarsalis and its vector competence for western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses; 2) To increase our knowledge of the relation of Cx. tarsalis survival, gonotrophic cycles, autogeny, diapause, dispersal and vector competence to summertime activity and overwintering of WEE and SLE viruses by field studies at selected sites in the Coachella and Imperial valleys of southeastern California; 3) To evaluate the hypothesis that acute or relapsing avian malarial infections in immunosuppressed birds will reactivate chronic or latent WEE and SLE viral infections in such hosts; 4) To conduct studies on the effect of environmental conditions during preimaginal development on the expression of vector competence in adult female Cx. tarsalis for WEE and SLE viruses; 5) To elucidate mechanisms which control susceptibility and resistance of Cx. tarsalis to WEE virus, including presence and absence of receptor sites on mesenteronal microvillar membranes and modulation of WEE viral titers; and 6) To develop dynamic system models to aid in the understanding of the underlying mechanisms involved in the maintenance and transmission of WEE virus.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Unknown (R22)
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Tropical Medicine and Parasitology Study Section (TMP)
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University of California Berkeley
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Kramer, L D; Hardy, J L; Presser, S B (1998) Characterization of modulation of western equine encephalomyelitis virus by Culex tarsalis (Diptera: Culicidae) maintained at 32 degrees C following parenteral infection. J Med Entomol 35:289-95
Reisen, W K; Lothrop, H D; Presser, S B et al. (1997) Landscape ecology of arboviruses in southeastern California: temporal and spatial patterns of enzootic activity in Imperial Valley, 1991-1994. J Med Entomol 34:179-88
Reisen, W K; Hardy, J L; Presser, S B (1997) Effects of water quality on the vector competence of Culex tarsalis (Diptera: Culicidae) for western equine encephalomyelitis (Togaviridae) and St. Louis encephalitis (Flaviviridae) viruses. J Med Entomol 34:631-43
Fulhorst, C F; Bowen, M D; Hardy, J L et al. (1996) Geographic distribution and serologic and genomic characterization of Morro Bay virus, a newly recognized bunyavirus. Am J Trop Med Hyg 54:563-9
Fulhorst, C F; Hardy, J L; Eldridge, B F et al. (1996) Ecology of Jamestown Canyon virus (Bunyaviridae: California serogroup) in coastal California. Am J Trop Med Hyg 55:185-9
Reisen, W K; Lothrop, H D; Hardy, J L (1995) Bionomics of Culex tarsalis (Diptera: Culicidae) in relation to arbovirus transmission in southeastern California. J Med Entomol 32:316-27
Eisenberg, J N; Reisen, W K; Spear, R C (1995) Dynamic model comparing the bionomics of two isolated Culex tarsalis (Diptera: Culicidae) populations: model development. J Med Entomol 32:83-97
Reisen, W K; Smith, P T; Lothrop, H D (1995) Short-term reproductive diapause by Culex tarsalis (Diptera: Culicidae) in the Coachella Valley of California. J Med Entomol 32:654-62
Reisen, W K; Hardy, J L; Lothrop, H D (1995) Landscape ecology of arboviruses in southern California: patterns in the epizootic dissemination of western equine encephalomyelitis and St. Louis encephalitis viruses in Coachella Valley, 1991-1992. J Med Entomol 32:267-75
Reisen, W K (1995) Effect of temperature on Culex tarsalis (Diptera: Culicidae) from the Coachella and San Joaquin Valleys of California. J Med Entomol 32:636-45

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